Automatic bucket positioning mechanism



Aug. 9, 1966 G. P. KOCH 3,265,229

AUTOMATIC BUCKET POSITIONING MECHANISM Filed Dec. 2, 1963 a Sheets-Sheet 1 INVENTOR.

Geozye P/d? Aug. 9, 1966 G. P. KOCH 3,265,229

AUTOMATIC BUCKET POSITIONING MECHANISM Filed Dec. 2, 1965 3 Sheets-Sheet 2 INVENTOR. Gen/ye AAfrc/r n United States Patent land Filed Dec. 2, 1965, Ser. No. 327,259 11 Claims. (tCl. Zl4140) This invention relates to a material handling apparatus such as loaders and the like and, in particular, to a front end loader characterized by means for automatically disposing the material handling bucket thereof in a low level digging position in response to lowering of the bucket-supporting boom from a, high lift dump position or the like.

Referring to front end loader vehicles as an example of one type of material handling apparatus with which the present invention may be used to advantage, such loader vehicles typically comprise a boom pivotally mounted on a mobile vehicle for raising and lowering movement relative thereto, a bucket pivotally mounted on an extreme end of the boom for movement between digging and dumping positions relative thereto, hydraulically operable boom and bucket jacks respectively suitably carried by the vehicle and connected to the boom and bucket to control movement thereof, and a suitable fluid pressure circuit means including manually operable boom and bucket selector valves to selectively control independent operation of the boom and bucket jacks and, hence, vertical movement of the boom and pivotal movement of the bucket thereon.

One typical cycle of operation of such a loader vehicle comprises approaching a load of material to be dug or otherwise picked up with the boom disposed in a lowered position and the bucket disposed relative thereto in a digging position; that is, with the floor of the bucket disposed in a generally horizontal material-receiving position although, of course, the digging position may be varied from the aforementioned position in accordance with other operating conditions such as, for example, the desire of the vehicle operator to dig down from ground level. In any event, after a load is dug, the vehicle operator will often operate the bucket selector valve to roll or curl the bucket rearwardly about its mounting on the boom to dispose the bucket in a low level load retaining position. Thereafter, the boom jacks will be energized by shiftinfi the boom selector valve to raise the boom to a desired position for subsequent dumping. When the desired boom elevation is reached, as with respect to a truck into which the contents of the bucket are to be dumped, the bucket selector valve in again shifted to this time roll or curl the bucket forwardly about its mounting on the boom to dispose the bucket in a dumping position; that is, a position in which the aforementioned floor of the bucket extends at an angle below a horizontal plane through the pivot axis of the bucket on the boom. As a result, the contents of the bucket are discharged. Thereafter, the vehicle operator will begin to manipulate both the boom and bucket selector valves in an effort to once again dispose the boom and bucket in their low level digging positions. In other words, either jointly or independently, the boom and bucket selector valves must be manipulated to again lower the boom while at the same time rolling the bucket rearwardly about its mounting on the boom to again assume the desired digging position.

As will be readily appreciately by those acquainted with this art, considerable skill, often lacking, is required of the operator of such a loader vehicle in efficiently and expeditiously returning the loader apparatus to the low level digging position while manipulating the selector valves aforementioned. However, even apart from Fatented August 9, 1966 PC I dexterity, coordination and timing required of the vehicle operator in this regard, a further problem is presented due to difliculty of observing the position of the bucket once it approaches ground level; that is, in the typical installation, the bucket is disposed in front of the vehicle relatively remote from the vehicle operators position and below his line of sight so that, even if he does efficiently return the boom and bucket to an approximate low level digging position, it is extremely difficult for him to make any final adjustment required to provide the actual bucket digging position desired.

In view of the foregoing considerations, the present invention is directed to a loader vehicle of the general type aforementioned comprising a boom pivotally mounted on a vehicle for movement between raised and lowered positions relative thereto, fluid pressure operated boom jacks operatively connected between the vehicle and boom to move the latter between its positions, a material handling implement, such as a bucket, pivotally mounted on the boom for movement between predetermined positions, such as digging and dumping positions, relative thereto, and fluid pressure operated bucket jacks operable on the bucket to move the latter between its positions aforementioned, and is particularly characterized by control means for automatically moving the bucket or other implement to its digging position or the like in response to movement of the boom toward its lowered position, thereby completely eliminating the requirement of any operator-attendance whatsoever to the bucket selector valve in finally disposing the bucket in the desired digging position.

More specifically in this regard, the present invention is particularly characterized by the fact that the fluid circuit means provided for supplying fluid under pressure to the boom and bucket jacks to accomplish their normal functions at all times communicates exhaust fluid from the boom jack as the boom is lowered to the bucket jack to tend to operate the latter to move the bucket from a dumping position to the digging position thereof, and control valve means are provided in such circuit means for controlling the flow of such exhaust fluid and to permit such flow so long as the bucket has not reached the desired digging position but, once such digging position is reached, such flow is interrupted while operating fluid may still be supplied to and exhausted from the boom jack in the event that it still requires further lowering.

More specifically, the present invention is further particularly characterized by the fact that the aforementioned control valve means comprises a first control valve having a first position preventing exhaust of fluid from and operation of the bucket jack independently of the bucket selector valve, and a second position permitting such exhaust and operation, the first control valve being movable automatically from its first to its second position in respone to the pressure of fluid being exhausted from the boo-m jack as the boom is lowered while the bucket is displaced from its final desired digging position, a second control valve having a first position preventing fluid exhausted from the boom jack from being returned to the source or low pressure side of the circuit means, and a second position permitting such return, and means operatively connecting the bucket to the second control valve to automatically dispose the latter in the first and second positions thereof, respectively, with the bucket in said dumping and digging positions thereof.

As a result, at any time that the bucket is displaced from the digging position toward the dumping position thereof, the aforementioned second control valve will occupy its first position aforementioned to prevent exhaust from the boom jack from being returned to source, and necessitating it to flow to and operate the bucket jack to move the bucket toward the digging position, ex-

haust from the bucket jack being supplied through the first control valve aforementioned which has been shifted to its second position as a result of the second control valve being disposed in the first position thereof. As soon as the bucket reaches its digging position, however, the second control valve is automatically disposed in its second position permitting exhaust fluid from the boom jack, as the boom may be further lowered, to be returned through the second control valve to the source to interrupt any further operation of the bucket jack.

The present invention is further characterized by the fact that, notwithstanding the fluid intercommunication between the bucket and boom jacks during automatic positioning of the bucket in a digging position as the boom is lowered, the bucket and boom jacks are otherwise completely independently operable in the manner of conventional loader vehicles.

In order to facilitate an understanding of the invention, a preferred embodiment thereof will now be described with reference to the enclosed drawings in which:

FIGURE 1 is a side elevational view of a loader vehicle illustrating a preferred embodiment of the invention, the loader linkage being shown in solid line in a low level digging position and in phantom line in a high lift dumping position;

FIGURE 2 is a schematic illustration of the hydraulic circuitry and components of the fluid power system of the vehicle of FIGURE 1;

FIGURE 3 is a sectional view of a control valve included in the system of FIGURE 2; and

FIGURE 4 is a sectional view of another control valve included in the system of FIGURE 2.

Referring now to the drawings, and particularly FIG- URE 1 thereof, the numeral generally indicates an agricultural tractor or other mobile vehicle having the usual ground-engaging wheels 12 and operators station 14. A front end loader linkage is indicated generally at 16 as being mounted on vehicle 10, such linkage preferably comprising paired booms or lift beams and associated bucket tilt linkages which are identical in construction. Thus, only one side of such linkage is shown in FIGURE 1.

Thus, each boom or lift beam 18 has one end thereof suitably pivotally mounted on a horizontal transverse axis 20 to the frame of the vehicle 10 and is adapted to be adjusted vertically relative to the vehicle between the positions illustrated in FIGURE 1 by a boom jack 22 having its cylinder element pivotally connected at 24 to the main frame of the vehicle and .the piston element reciprocably disposed therein [pivotally connected at 26 to the boom intermediate the ends of the latter.

A conventional loader bucket 28 is pivotally mounted on the horizontal transverse axis 30 on and between the forward ends of the booms 18. Rolling movement of the bucket 28 between the low level digging position and high lift dumping position illustrated tn FIGURE 1 is controlled by a bucket tilt linkage of which there is usually a pair as aforementioned, one for each lift beam or boom 18. Each such tilt linkage is illustrated as comprising a bucket tilt jack 32 having the cylinder element thereof pivotally connected at 34 to the boom 18 intermediate the ends of the latter and the relatively reciprocable piston member pivotally connected at 36 intermediate the ends of a tilt lever 38 pivotally connected at 40 to the boom 18 and at 42 to one end of a tilt link 44 having its other end pivotally connected at 46 to the bucket on an axis spaced from the axis of the pivotal connection 30 of the latter on the booms. As will be appreciated, extension and retraction of the boom jacks 22 under fluid pressure and in a manner to be described more fully hereinafter will result, respectively, in rais ing and lowering of the booms 18 between the positions illustrated in FIGURE 1. In similar fashion, extension and retraction of the bucket tilt jacks 32 will result, respectively, in rolling the bucket clockwise and counterclockwise in FIGURE 1 between dumping and digging positions relative to the booms and the ground.

The fluid system for controlling operation of the aforedescribed construction comprises a reservoir 48 for a suitable operating fluid, such as oil, for delivery through the filter 50 to the inlet of a suitable pump 52 which discharges such fluid under a suitable and desired pressure to the inlet gallery 54 of a valve manifold illustrated at 56 in FIGURE 1 as mounted at operators station 14, and housing the bucket and boom selector valves indicated generally and respectively at 58 and 60 in FIG- URE 2. As is indicated in FIGURES 1 and 2, both the bucket and boom selector valves are the type including a manually shiftable valve spool op eratively connected to the pivotal operating levers 62. Furthermore, and as further illustrated, the selector valves are of the self-centering type; that is, of the type in which spring means are utilized to normally dispose the shiftable valve spools in a neutral or centered position preventing any flow Whatsoever from the gallery 54 through the respective valves to the various instrumentalities controlled thereby and, to further prevent any such reverse flow of fluid from such instrumentalities through such valves to the reservoir.

It will be seen that one port 64 of the bucket selector valve 58 communicates through the conduit 66 and branch conduit 68 with the piston rod sides of the respective bucket tilt jacks 32, while the piston head sides thereof are connected through the branch conduit 70, conduit 72 and conduit 74 to the other port 76 of the bucket selector valve 58.

In somewhat similar fashion, one port 78 of the boom selector valve 60 is connected through the conduit 80 and the branch conduit 82 to the piston rod sides of the respective boom jacks 22, while the piston head sides thereof are communicated through the branch conduit 84, conduit 86, control valve 88 suitably mounted on one of the booms 18, and conduits 90 and 92 to the other port 94 of the boom selector valve.

More specifically in this regard, and referring particularly to FIGURES 2 and 4, the control valve 88 comprises the valve body 96 including the port 98 communicating with conduit 36, opposed port 100 communicating through the one-way check valve 102 with the conduit 90, and the port '104 communicating freely with the conduit 90. A conventional valve spool 106 having the axially spaced valve lands 108 is reciprocably disposed within the valve body 96 to control flow of fluid therethrough in a manner to be described hereinafter, the spring element 110 at one end of the spool continuously biasing the latter to the left in FIGURES 2 and 4 toward and to the position therein illustrated. The other end of the valve spool is connected through the spring element 112 illustrated particularly in FIGURE 1 and cable or similar motion-transmitting mechanism 114 to one of the tilt levers 38 so as to position the spool in accordance with the position of the bucket relative to the booms.

In FIGURES 1, 2 and 4, the control valve spool 106 is shown in its extreme leftward position which is the position it assumes immediately upon the bucket 28 reaching the digging position illustrated in full line in FIGURE 1. In such position, it will be manifest that fluid in the conduit 86 may flow from port 98 to port 104 and through the conduits 90 and 92 to the boom selector valve 60. However, with the bucket rolled to the dumping position illustrated in phantom line in FIGURE 1, the spool 106 will be shifted to an extreme position to the right in FIGURES 2 and 4 wherein the lift valve land 1108 prevents communication between the ports 98 and 104 of the control valve and, due to the presence of the one-way check valve 102, fluid may not flow from the conduit 86 through control valve 83 to the conduit 90 and back to the boom selector valve. On the other hand, whether the spool of the control valve 88 is in the posie3 tion shown in FIGURES 2 and 4 or shifted to the extreme right as aforedescribed, it will be immediately clear that fluid may at all times flow from the conduit 92 through either the port 1% or past the check valve N2 and through the port Itttl to the port 93, depending upon the particular position of the valve spool.

Another control valve I16 is suitably fixedly mounted on one boom 18, and is associated with the hydraulic circuitry aforedescribed and, referring particularly to FIGURES 2 and 3, comprises a valve body 118 having the port lit-ti communicating with conduit as, port 122 communicating through the one-Way check valve I24 with the branch conduit es, the port I26 communicating through the one-Way check valve 128 with the conduit 72 and branch conduit 74), and the port 1% communicating with the conduits 9t? and 92. A conventional valve spool 132 is axially shiftably mounted within the valve body 113 and includes the valve lands I34 and 136 respectively controlling communication between the respective pairs of ports 12%) and 122, and and l3). The land 134 includes axially undercut portions 138 serving to insure communication between the ports IZtl and 122 in the position thereof illustrated in FIGURES 2 and 3, as well as all other positions thereof as will become apparent hereinafter. The spring construction 14d at one end of the spool continuously biases the latter to the right and to the position illustrated in FIGURES 2 and 3, while permitting shifting movement of the spool to the left to respectively communicate ports 12 h and 122 and ports I26 and 136 for free unrestricted communication therebetween. With the spool disposed in the position of FIG- URES 2 and 3, the port 11% will communicate with the port 122 as aforementioned, but no flow is possible between the ports 126 and 13th.

Referring now to the operation of the aforedescribed loader vehicle, it may be assumed that the loader linkage l6 and the components of the hydraulic circuitry associated therewith are all in the positions illustrated in the drawings; that is, that the booms 18 are lowered and the bucket 23 is disposed in its low level digging position as illustrated in full line in FIGURE 1, with the bucket and boom selector valves 58 and oil in their neutral positions and the control valves 88 and M6 in the positions illustrated. It may now be further assumed that a load of material has been received in the bucket in the full line position of FIGURE 1, and that the vehicle operator now wishes to transfer the load for dumping into a truck or the like. At this time, he may shift the bucket selector valve 58 to the left in FIGURE 2 to communicate fluid under pressure from the manifold gallery 5d through the port (:4 to the conduit 66. Fluid under pressure is thus supplied through the branch conduit 6% to the piston rod sides of the bucket tilt jacks 32 to cause them to retract to roll the bucket counterclockwise in FIGURE 1 about the pivot axis 30 to a low level load-retaining position in which the mouth of the bucket is disposed substantially horizontal to cradle the load in a non-spilling attitude relative to the ground. Check valve I24 prevents fluid so supplied from being communicated to control valve llo. As the bucket tilt jacks are retracted in this manner, fluid is exhausted from the piston head sides thereof through the branch conduit 7%, conduit '72 and conduit 7&- to and through the port 76 of the bucket selector valve to reservoir. Although fluid being exhausted from the bucket jacks may open the check valve 12% in conduit 72, it will be clear that fluid may not flow from the conduit 72 between the ports I26 and 13d of control valves I16 since the valve land 1% of the spool valve 132 prevents such flow, thereby insuring that all exhaust fluid from the bucket tilt jacks is returned to reservoir. The operator then releases lever 62 associated with the bucket selector valve to allow the latter to return to its neutral or centered position.

With the load so cradled, the vehicle operator may now shift the boom selector valve 6b to the left in FIGURE 2 to supply fluid under pressure from the manifold gallery 54- through the valve port 94 to the conduit 92, conduit 9% port 164- and past spool 1% of control valve 855 to port 93 thereof and conduit as to the branch conduit 34- and the piston head sides of the boom jacks 22. Thus, the boom jacks will be extended to raise the boom toward and to the phantom line position of FIGURE 1. As the boom is so raised, fluid is exhausted from. the piston rod sides of the boom jacks into the branch conduit 82 and conduit 8% through the port 78 of the boom selector valve to reservoir. The boom selector valve is allowed to return to its neutral position after the booms have reached the desired elevation.

At this juncture, it should be noted that pressurization of the piston head sides of the boom jacks 22 for the purpose and in the manner aforedescribed results in delivery of fluid under pressure from the conduit 92 through the port list? to the interior of the valve body 118 of control valve 116 between the valve lands 134 and 136. Due to the equal opposed areas of such lands, however, no shifting movement of the valve spool 132 occurs solely by reason of such pressure. However, such fluid under pressure is also delivered through the control valve 88 to the conduit as in the manner aforedescribed, and such conduit as communicates with the port 12% and through the undercut portions 1355 in the valve spool land 134 to the port 122. Fluid so flowing from the port to the port 122 will act upon the right-hand end of the valve spool land 134 to overcome the balanced pressure condition between the valve lands 134 and 136 and cause the valve spool to shift to the left in FIGURES 2 and 3 against the influence of spring Ml Pressure in the conduit 92 is then available to flow from the port to the port 126 and into the conduit 72, but cannot flow any further due to the presence of the check valve 123. Thus, pressurization of the boom jacks in this manner does not extend the bucket jacks 32. Furthermore, operating fluid is prevented from flowing past check valve 124 to the rod sides of bucket jacks 32 to retract the latter, since fluid is trapped in the piston head sides thereof with the bucket selector valve 58 in its neutral position.

When the booms are elevated to the desired height as indicated by the phantom line position of FIGURE 1, the vehicle operator will then shift the bucket selector valve 58 to the right. As a result, pressure from the manifold gallery 54 will be communicated through port 76 to the conduit 74, conduit 72 and, hence to the branch conduit 70 and the piston head sides of the bucket tilt jacks 32. Fluid in conduit 72 is prevented from flowing past check valve 12$ and control valve 116 since the latter is in the position illustrated. As a result, the jacks are extended to pivot the tilt levers 38 clockwise in FIGURES 1 and 2 to dump the bucket as illustrated in phantom line in FIGURE 1. In so dumping the bucket, exhaust fluid from the piston rod sides of the bucket tilt jacks is returned through branch conduit 68, conduit 66 and port 64 of the bucket selector valve to reservoir. Such exhaust of the bucket tilt jacks is prevented from communicating with the control valve 116 by means of the one-way check valve 124. The operator allows the bucket selector valve 58 to return to its neutral position after the bucket is dumped.

As soon as the bucket 28 is rolled clockwise from the position it occupies on and relative to the booms which provide a digging position when the booms are lowered as aforementioned, the valve spool me of the control valve 88 is shifted to the right in FIGURES 2 and 3 to prevent communication between the ports 98 and M4. Furthermore, to the extent that clockwise roll of the bucket to a dumping position exceeds the extent of travel permissible of the spool res relative to the valve body 96, the spring 112 forming a part of the connection between the valve spool res and the rod or cable mechanism 114 accomodates such additional bucket motion in the manner of a lost motion connection. It will also be apparent at this point that the relative positions of the booms and bucket at which the latter will shift spool res, thereby determin- 7 ing the digging position desired, may be adjusted by adjusting the length of the cable or rod 114.

After dumping the bucket in this manner, the vehicle operator may shift the boom selector valve 60 to the right in FIGURE 2 to communicate fluid pressure from the inlet gallery 54 through the port 78 to the conduit 80, and through the branch conduit 82 to the rod sides of the boom jacks 22. As a result, the boom jacks are retracted and lower the booms from the phantom line to the full line position of FIGURE 1. As these jacks are so retracted, fluid exhausted from the piston head sides thereof is communicated through the branch conduit 84 and conduit 86 to the port 98 of control valve 88. However, with the bucket still displaced from its desired digging position, the valve spool 106 remains in its shifted position to the extreme right in FIGURES 2 and 4 thereby preventing any communication from port 98 to port 104. Consequently, since flow from the control valve 88 from port 100 is prevented by the one-way check valve 102, exhaust fluid from the boom jacks is trapped in the conduit 86. As a consequence, the pressure of such exhausted fluid enters the port 120 of control valve 116 and passes through the undercut portions 138 of valve spool land 134 to act upon the right end of the latter and shift the valve spool to the left in FIGUR-ES 2 and 3. As a result of such movement, the port 120 communicates with the port 122 to supply exhaust fluid from the boom jacks past the one-way check valve 124 to branch conduit 68 and the rod sides of the bucket tilt jacks 32. As a result, the bucket tilt jacks begin to retract while exhaust fluid therefrom flows through the branch conduit 70, and is prevented from flowing through the conduit 74 and bucket selector valve 58 since the latter is in its neutral position. However, such exhaust fluid flows through the conduit 72 and past one-way check valve 128 to the port 126 of control valve 116. Since the valve spool of the latter valve is shifted to the left, the exhaust fluid from the tilt jacks is further communicated from the port 126 to the port :130 and conduit 92, and through the port 94 of the boom selector valve to reservoir.

Either at the time that the booms 18 reach their extreme lowered position or some time prior thereto, usually the latter, the fluid interchange between the boom jacks and bucket tilt jacks as aforedescribed will have sufliciently retracted the bucket tilt jacks so as to automatically result in disposition of the bucket 28 in the desired low level digging position once the booms reach their lowered position. When such digging position is reached, and as sensed by pivotal movement of the tilt lever 38 and the connection of the latter to the valve spool 106, the control valve 88 is returned to the position illustrated in FIGURES 2 and 4. At this time, the port 98 of the control valve is immediately communicated with the port 104 thereof for flow of boom jack exhaust fluid from the conduit 86 through the ports 98 and 104 to the conduits 90 and 92 and through the port 94 of the boom selector valve to reservoir. Since exhaust fluid from boom jacks is now free to return through the conduit 86 to reservoir in this manner, pressure is relieved from the right-hand end of the valve spool land 134 of control valve 116 resulting in the spring 140 shifting the latter to the right in FIGURES 2 and 3. As a result, valve land 136 prevents any further flow of exhaust fluid from the bucket tilt jacks through the conduit 72 to ports 126 and 130. Hence, the bucket is automatically disposed in its digging position relative to the booms. When the booms reach the desired lowered position, the boom selector valve 60 is released and thereby automatically returns to its neutral position.

From the foregoing description, it will now be apparent that the present invention functions to automatically roll a loader bucket from a high lift dumping position to a low level digging position relative to a vertically adjustable boom in response to lowering of the latter. By the same token, raising of the boom or pivotal movement of the bucket on the boom in either of two directions may be accomplished totally independently from lowering movement of the boom. Furthermore, the bucket may be pivoted in either direction on the boom irrespective of the elevation of the boom at any given time. In other words, although lowering of the boom will automatically result in moving the bucket from the phantom line dumping position toward the full line digging position, it may for one reason or another be desired to stop the boom at an elevation intermediate those illustrated in FIGURE 1. At any such intermediate elevation, it will be readily apparent that actuation of the bucket selector valve 58 will result in pivotal movement of the bucket on the boom independently of operation of the boom jacks 22. In short, the loader linkage 16 of the present invention provides all of the advantages of independent actuation of the boom and bucket of a conventional loader, while additionally providing for concert movement of the bucket and boom when lowering the latter from a high lift dumping position to automatically dispose the bucket in a low level digging position without any attention whatsoever of the vehicle operator.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In the combination comprising a material handling implement pivotally mounted on boom means for movement toward and from a predetermined position relative thereto, said boom means being pivotally mounted for raising and lowering movement thereof, and fluid pressure operated implement and boom means jacks respectively operable to move said implement and boom means; the improvement comprising fluid circuit means interconnecting said implement and boom means jacks, and control valve means in said circuit means operably connected to said implement to sense a position of the latter displaced from said predetermined position thereof, said control valve means being operable automatically in response to displacement of said implement from said predetermined position thereof and actuation of said boom means to lower the latter to move said implement toward said predetermined position thereof.

2. In the combination comprising a material handling implement pivotally mounted on boom means for movement toward and from a predetermined position relative thereto, said boom means being pivotally mounted for raising and lowering movement thereof, and fluid pressure operated implement and boom means jacks respectively operable to move said implement and boom means; the improvement comprising fluid circuit means interconnecting said implement and boom means jacks, and control valve means in said circuit means operably connected to said implement to sense a position of the latter displaced from said predetermined position thereof, said control valve means being operable automatically in response to displacement of said implement from said predetermined position thereof and actuation of said boom means to lower the latter to supply fluid from said boom means jack to said implement jack and automatically move said implement toward said predetermined position thereof.

3. The combination according to claim 2 wherein said control valve means is operable automatically to discontinue supply of fluid from said boom means jack to said implement jack upon said implement reaching said predetermined position thereof.

4. In the combination comprising a vehicle, boom means pivotally mounted on said vehicle for movement between raised and lowered positions relative thereto, fluid pressure operated boom jack means operatively interconnecting said vehicle and boom means and operable to move the latter between said positions thereof, a material handling bucket pivotally mounted on said boom means for movement between digging and dumping positions relative thereto, and fluid pressure operated jack means operable to move said bucket between said positions thereof; the improvement comprising fluid circuit means interconnecting said boom and bucket jacks, and

9 control valve means in said circuit means operably connected to said bucket to sense said dumping position thereof, said control valve means being operable automatically in response to said bucket being in said dumping position thereof and actuation of said boom means to lower the latter to supply fluid from said boom jack means to said bucket jack to automatically operate the latter and move said bucket toward said digging position thereof.

5. The combination according to claim 4 wherein said control valve means is operable automatically to discontinue supply of fluid from said boom jack means to said bucket jack upon said bucket reaching said digging position thereof.

6. In the combination comprising a vehicle, boom means pivotally mounted on said vehicle for movement between raised and lowered positions relative thereto, fluid pressure operated boom jack means operatively interconnecting said vehicle and boom means and operable to move the latter between said positions thereof, a material handling bucket pivotally mounted on said boom means for movement between digging and dumping positions relative thereto, and fluid pressure operated bucket jack :means operable to move said bucket between said positions thereof; the improvement comprising fluid circuit means interconnecting said boom and bucket jack means, the improvement comprising first control valve means having a first position preventing flow of operating fluid from said boom jack means to said bucket jack means to operate the latter and a second position to permit such flow to supply fluid being exhausted from said boom jack means as said boom is lowered to said bucket jack means to operate the latter and move said bucket toward said digging position thereof, said first control valve means being movable automatically from said first to said second position thereof in response to the pressure I of fluid being exhausted from said boom jack means as said boom is lowered with said bucket in said dumping position thereof, second control valve means having a first position preventing flow of fluid being exhausted from said boom jack means to a low pressure side of said circuit means and a second position permitting such flow, and means operatively connecting said bucket to said second control valve means to automatically dispose the latter in said first and second positions thereof, respectively, with said bucket in said dumping and digging positions thereof.

7. In the combination comprising a vehicle, boom means pivotally mounted on said vehicle for movement between raised and lowered positions relative thereto, fluid pressure operated boom jack means operatively interconnecting said vehicle and boom means and operable to move the latter between said positions thereof, a material handling bucket pivotally mounted on said boom means for movement between digging and dumping positions relative thereto, and fluid pressure operated bucket jack means operable to move said bucket between said positions thereof; the improvement comprising fluid circuit means interconnecting said boom and bucket jack means, said fluid circuit means at all times communicating exhaust fluid from said boom jack means as said boom is lowered to said bucket jack means to tend to operate the latter to move said bucket from said dumping to said digging position thereof, first control valve means having a first position preventing exhaust of fluid from and operation of said bucket jack means and a second position permitting such exhaust and operation, said first control valve means being movable automatically from said first to said second position thereof in response to the pressure of fluid being exhausted from said boom jack means as said boom is lowered with said bucket moved from said digging position thereof, second control valve means having a first position preventing flow of fluid being exhausted from said boom jack means as said boom means is lowered to a low pressure side of said circuit means and a second position permitting said flow, and

ltd means operatively connecting said bucket to said second control valve means to automatically dispose the latter in said first and second positions thereof, respectively, with said bucket in said dumping and digging positions thereof.

8. The combination according to claim 7 wherein said circuit means further comprises a boom selector valve for selectively supplying operating fluid to said boom jack means, and wherein operating fluid may be supplied from said boom selector valve through said second control valve means to said boom jack means in either of said positions of said second control valve means.

9. The combination according to claim '7 further comprising check valve means permitting one-way flow of fluid from said boom jack means through said first control valve means to said bucket jack means while preventing reverse flow therebetween during movement of said bucket jack means and said bucket from said digging to said dumping position of the latter.

10. In the combination comprising a vehicle, boom means pivotally mounted on said vehicle for movement between raised and lowered positions relative thereto, fluid pressure operated boom jack means operatively interconnecting said vehicle and boom means and operable to move the latter between said positions thereof, a material handling bucket pivotally mounted on said boom means for movement between digging and dumping positions relative thereto, and fluid pressure operated bucket jack means operable to move said bucket between said positions thereof; the improvement comprising fluid circuit means interconnecting said boom and bucket jack means, control valve means in said circuit means for automatically moving said bucket from said dumping to said digging position thereof in response to lowering said boom means, said control valve means comprising first control valve means having a first position preventing flow of operating fluid from said boom jack means to said bucket jack means to operate the latter and a second position to permit such flow to supply fluid being exhausted from said boom jack means as said boom is lowered to said bucket jack means to operate the latter and move said bucket toward said digging position thereof, said first control valve means being movable automatically from said first to said second position thereof in response to the pressure of the fluid being exhausted from said boom jack means as said boom means is lowered with said bucket in said dumping position thereof, second control valve means having a first position preventing flow of fluid being exhausted from said boom jack means to a low pressure side of said circuit means and a second position permitting such flow, and means operatively connecting said bucket to said second control valve means to automatically dispose the latter in said first and second positions thereof, respectively, with said bucket in said dumping and digging positions thereof, said last-named means comprising extensible spring means to accommodate further movement of said bucket from said digging toward said dumping posit-ions thereof after said second control valve means has been moved to said first position thereof.

11. In the combination comprising a vehicle, boom means pivotally mounted on said vehicle for movement between raised and lowered positions relative thereto, fluid pressure operated boom jack means operatively interconnecting said vehicle and boom means and operable to move the latter between said positions thereof, a material handling implement pivotally mounted on said boom means for movement toward and away from a predetermined position relative thereto, and fluid pressure operated implement jack means operable to move said implement between said positions thereof; the improvement comprising fluid circuit means interconnecting said boom and implement jack means, control valve means in said circuit means for automatically moving said implement between said positions thereof in response to lowering said boom means, said control valve means comprising first control valve means having a first position preventing flow of operating fluid from said boom jack means to said implement jack means to operate the latter and a second position to permit such flow to supply fluid being exhausted from said boom jack means as said boom is lowered to said implement jack means to operate the latter and move said implement toward said predetermined position thereof, said first control valve means being movable automatically from said first ,to said second position thereof in response to the pressure of the fluid being exhausted from said boom jack means as said boom means is lowered with said implement in said dumping position thereof, second control valve means having a first position preventing flow of fluid being exhausted from said boom jack means to a low pressure side of said circuit means and a second position permitting such flow', and means operat ively connecting said implement to said second control valve means to automatically dispose the latter in said first and second positions thereof, respectively, with said implement in a position away from and in said predetermined position thereof, said last-named means comprising means to accommodate further movement of said implement from said predetermined position thereof after said second control valve means has been moved to said first position thereof.

References Cited by the Examiner UNITED STATES PATENTS HUGO O. SCHULZ, Primary Examiner. 

1. IN THE COMBINATION COMPRISING A MATERIAL HANDLING IMPLEMENT PIVOTALLY MOUNTED ON BOOM MEANS FOR MOVEMENT TOWARD AND FROM A PREDETERMINED POSITION RELATIVE THERETO, SAID BOOM MEANS BEING PIVOTALLY MOUNTED FOR RAISING AND LOWERING MOVEMENT THEREOF, AND FLUID PRESSURE OPERATED IMPLEMENT AND BOOM MEANS JACKS RESPECTIVELY OPERABLE TO MOVE SAID IMPLEMENT AND BOOM MEANS; THE IMPROVEMENT COMPRISING FLUID CIRCUIT INTERCONNECTING SAID IMPLEMENT AND BOOM MEANS JACKS, AND CONTROL VALVE MEANS IN SAID CIRCUIT MEANS OPERABLY CONNECTED TO SAID IMPLEMENT TO SENSE A POSITION OF THE LATTER DISPLACED FROM SAID PREDETERMINED POSITION THEREOF, SAID CONTROL VALVE MEANS BEING OPERABLE AUTOMATICALLY IN RESPONSE TO DISPLACEMENT OF SAID IMPLEMENT FROM SAID PREDETERMINED POSITION THEREOF AND ACTUATION OF SAID BOOM MEANS TO LOWER THE LATTER TO MOVE SAID IMPLEMENT TOWARD SAID PREDETERMINED POSITION THEREOF. 